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Biomedical subjects

S Lloyd

Publications and source records attributed to S Lloyd.

At least 163 records · Page 9Linked to original sources
PubMed1984

Macrophage mediated resistance to Babesia microti in Nematospiroides dubius--infected mice.

Infection with the gastrointestinal nematode, Nematospiroides dubius, induced resistance to a concurrent infection with Babesia microti in mice. This enhanced resistance to B. microti occurred during infection with the larval, rather than the adult stages of N. dubius. Splenectomy or the injection of carrageenan or silica abrogated the protective effect against B. microti induced by infection with N. dubius. Peritoneal macrophages harvested from infected mice produced inhibition of the development of B. microti in vitro. This inhibition was greatest using macrophages harvested from mice recovered from infection with B. microti and from mice infected with the larval stages of N. dubius. Also, supernatants harvested from cultures of macrophages from N. dubius-infected mice suppressed B. microti development in vitro.

Animals↗
PubMed1984

Immunological unresponsiveness of lambs to infection with Haemonchus contortus. Modulation of responsiveness by exposure to soluble larval antigen.

The in vitro transformation of lymphocytes in the presence of antigen was used to assay the response of lambs to antigens of Haemonchus contortus. Neither uninfected lambs nor lambs infected with H. contortus up to 9 weeks of age developed in vitro lymphocyte responsiveness to antigen. A slight and transient increase in reactivity was demonstrable in some of the infected lambs when these were reinfected with H. contortus at 26 weeks of age. This lack of responsiveness could be modulated through the exposure of lambs, early in neonatal life, to multiple parenteral injections of soluble third stage larval antigen of H. contortus. Thus, antigen specific responses were apparent in the lymphocytes from 21-week-old lambs if these were injected with antigen when 2 to 17 weeks of age. In particular, marked antigen specific reactivity developed in 19- or 24-week-old lambs if such lambs were injected with antigen on five occasions over the first 6 weeks of life and subsequently infected with H. contortus when 7 weeks old. This responsiveness was enhanced when the lambs were reinfected with H. contortus at 26 weeks of age.

Animals↗
PubMed1984

Immunological unresponsiveness of lambs to infection with Haemonchus contortus. Effect of infection in the ewe on the subsequent responsiveness of lambs.

Specific antigen-induced lymphocyte transformation in vitro and haemagglutinating antibody responses were absent from lambs infected with Haemonchus contortus. However, when lambs were injected with soluble third stage larval antigen of H. contortus, given on five occasions during the first 6 weeks of life, specific antigen-induced lymphocyte transformation and haemagglutinating antibodies were induced to the antigen. In particular, a periparturient increased susceptibility to infection and the resultant presence of heavy infections with H. contortus in ewes appeared to prime their lambs to respond and marked lymphocyte transformation was observed in antigen injected lambs born of heavily infected ewes. The enhancement of this response was associated with the colostral transfer of as yet unidentified factors. The superimposition of an infection with H. contortus in lambs which had been stimulated to respond to antigen, suppressed the in vitro responsiveness of their lymphocytes. Although individual variation was apparent, a direct correlation between the presence of in vitro antigen-induced lymphocyte transformation to third stage larval antigen and susceptibility to infection occurred.

Animals↗
PubMed1984

In vitro induction of lymphocyte responsiveness by a Strongylus vulgaris-derived mitogen.

Proliferation in vitro of peripheral blood lymphocytes both from horses infected with Strongylus vulgaris and from helminth-free ponies was observed in the presence of extracts of the fourth and fifth stage larvae and adults of S. vulgaris. In addition, S. vulgaris extracts induced transformation in cultures of peripheral blood lymphocytes from sheep and dogs and in mouse spleen cell cultures. Nylon wool non-adherent, T cell enriched fractions of lymphocytes from both mice and horses were stimulated by the S. vulgaris larval mitogen while no proliferation was observed in cultures containing nylon wool adherent, B cell enriched fractions. Macrophage co-operation appeared not to be necessary for S. vulgaris mitogen-induced transformation of spleen cells. The S. vulgaris mitogen stimulated a subpopulation of mouse spleen cells different from those responsive to PHA, Con A and LPS. These cells might be T helper cells since B cells were stimulated to proliferate in the presence of both T cells and S. vulgaris larval mitogen. In addition, the supernatant of in vitro cultured larvae of S. vulgaris induced slight, but significant transformation of equine peripheral blood lymphocytes. Therefore, it is possible that the S. vulgaris mitogen released by both viable parasites and degenerating larvae might induce T cell dependent production of immunoglobulin in vivo and account for the beta-globulinaemia, of which IgG(T) is a major component, in S vulgaris infected horses.

Animals↗
PubMed1984

Babesia microti in mice. Adoptive transfer of immunity with serum and cells.

Protection against infection with Babesia microti in mice was passively transferred with either serum or cells. Immune spleen cells were more effective than were immune mesenteric lymph node (MLN) cells in reducing parasitaemias in recipient mice, and the level of protection correlated with the donor to recipient ratio rather than with the number of cells transferred. Protection against primary infection in recipient mice was adoptively transferred by nylon wool adherent, B cell enriched subpopulations of spleen cells. In contrast, higher peak parasitaemias were apparent in mice which received nylon wool non-adherent, T enriched spleen cells in comparison with the control mice. However, if the recipient mice were reinfected, control of this second infection was greatest in the recipients of the T enriched cell subpopulation. Treatment of the protective nylon wool adherent, B cell subpopulation with anti-theta serum and complement abolished both the protective effect and the anamnestic antibody response in the recipient mice. This suggested that primed T cells controlled the expression of the protective antibody response by primed B cells.

Animals↗
PubMed1984

Babesia microti in mice. Subpopulations of cells involved in the adoptive transfer of immunity with immune spleen cells.

Protection against a primary Babesia microti infection in mice, induced by the adoptive transfer of immune spleen cells, was abolished when the immune spleen cells were treated with mitomycin C prior to transfer. Since mitomycin C treatment prevents the replication of lymphocytes without affecting other cell functions, these results would suggest that the transferred cells required proliferation in the recipient mice before they could exert their protective effect, and this excludes the already differentiated antibody-forming cells (AFC's), macrophages and sensitised helper T cells. This was partly supported by the finding that Sephadex G-10 non-adherent immune cells, depleted of macrophages and AFC's, still conferred a strong protection after transfer. However, the Sephadex G-10 adherent cells, on a cell to cell basis, initially conferred a better protection against B. microti than did the non-adherent cells or unfractionated immune spleen cells. The possibility of the retention of an intermediate B memory cell type on the Sephadex G-10 columns and the suppression of antibody production are discussed in view of these results.

Animals↗
PubMed1984

Broken dreams: a study of the effects of divorce and depression on dream content.

To investigate the dream characteristics associated with a major life change, 29 women (ages 30-55) undergoing divorce were studied six nights in a sleep laboratory. The group was stratified on a self-report depression scale (the Beck Depression Inventory) into a depressed (N = 19, mean = 23.2) and nondepressed (N = 10, mean = 8.2) group and compared to a nondepressed married group who had never considered divorce. The dreams of those divorcing without major mood upset were longer and dealt with a wider time frame than those of the other two groups. They also dealt with marital status issues which were absent in the dreams of the depressed group. On follow-up those who had been depressed showed positive dream changes in mood, dreamlike quality, and identification of dream self with the marital role. The study suggests that some dream characteristics respond adaptively during life changes but that this is delayed when subjects are depressed. This raises the possibility of a corrective intervention for such persons.

Adult↗
PubMed1983

Neurochemical effects of long-term ingestion of ethanol by Sinclair (S-1) swine.

Sinclair (S-1) miniature swine were given access to a mixture of ethanol and beer for three years. Control swine were fed an isocaloric diet with corn starch substituted for ethanol. Both groups had free access to tap water. The alcohol group consumed about 4 g ethanol/kg/day (about 50% of their caloric intake) resulting in plasma ethanol concentrations of about 100 mg/dl. Brain membranes were prepared for analysis of neurotransmitter receptor binding, membrane lipid composition and physical properties. Receptor studies demonstrated an increase in the binding of 3H-GABA to cortical and cerebellar membranes from the alcoholic pigs as compared to control. Binding of 3H-ligands to muscarine cholinergic, beta-adrenergic, alpha-adrenergic, dopamine and benzodiazepine receptors was not changed by chronic ethanol ingestion. These results are similar to those obtained in studies of human alcoholics by other investigators. The cholesterol content of myelin and synaptic plasma membranes was not altered by ethanol consumption. The fluorescence polarization of diphenylhexatriene, a measure of membrane order, did not detect any differences in the membranes from control or alcohol-treated swine either before or after in vitro exposure to ethanol. These results are different from those reported for rodents after short-term ethanol treatments and emphasize the importance of evaluating different models of experimental alcoholism.

Alcohol Drinking↗
PubMed1983

Service workers' responses to abuse of the elderly.

The social service providers and physicians who encounter elder abuse have several potential avenues of intervention open to them in helping the elderly. Practice and training issues are discussed that are relevant for improving interventions and referrals in cases of family abuse of the elderly.

Aged↗
PubMed1981

Infection with gastrointestinal helminths. Effect of lactation and maternal transfer of immunity.

Lactation in sheep and mice was associated with a marked increase in susceptibility to newly acquired infection with Haemonchus contortus and Nematospiroides dubius, respectively. In sheep this increased susceptibility to infection with H. contortus occurred in late pregnancy and during lactation and was seen when the ewes were infected with both a single large dose of infective larvae and a "trickle" infection of 200 and 400 infective larvae of H. contortus given weekly for 14 weeks. Nonlactating ewes whose lactation had been terminated were able to reject the parasites which had been acquired in late pregnancy. A relaxation in the protective immune response was evident in immunized mice infected during lactation with N. dubius. However, despite this periparturient relaxation of immunity mice were capable of inducing a marked passive transfer of immunity to their offspring. Thus, neonatal mice born of mothers one or two months after the end of the immunizing schedule were protected against infection with N. dubius at 12 or 20 days of age.

Animals↗
PubMed1981

The effect of corticosteroid therapy on infection with Toxocara canis in dogs.

Three, six-month-old dogs were infected with 2,000 eggs of Toxocara canis. Three weeks after infection 15 immature adult parasites were found in the intestine of the dog which had been treated with high doses of corticosteroids (2 ml of Opticortenol S given every four days) while no parasites were found in the intestine of the dog treated with repeated injections of 0.3 ml Opticortenol S or in the untreated control dog. The increased susceptibility to infection with T. canis in the dog treated with high doses of corticosteroids was associated with a decrease in in vitro lymphocyte responsiveness to the mitogen concanavalin A and pokeweed mitogen and with a complete suppression of the eosinophilia that was seen 10 days after infection in the untreated control dog.

Animals↗